Bicycle sharing enterprises typically allow a user to rent one of a fleet of bicycles for a specified amount of time and/or for a specified fee. Such bicycles are often stored in locking stations or racks, to which the bicycles are securely fixed when not in use. Although the locking mechanisms of such bicycle racks can secure the bicycles, they have very limited, if any, means for storing additional accessories, such as helmets. However, many bicyclists prefer to use helmets for safety reasons and, in some areas helmets are required to be worn when riding bicycles. Accordingly, these and other deficiencies of conventional bicycle racks render them inadequate for many riders and improvements to the locking mechanisms of bicycle racks for bicycle sharing enterprises are desirable.